Refrigerating apparatus



July 26, 1932. KlNG 1,868,907

REFRIGERATING APPARATUS Filed OGE. 31. 1928.

Patented July 26, 1932 .UNI TED STAT ES PATENT OFFICE JESSE G. KING, OFDAYTON, OHIO, ASSIGNOB TO FBJ IGIDAIR E CORPORATION, OF DAYTON,

' OHIO, A CORPOBATTFON OF DELAWARE REFRIGERATING APPARATUS Applicationliled October 31, 1928, Serial li 'o. 316,274.

This invention relates to refrigerating apparatus and particularly to animproved form of refrigerating element or evaporator.

One of the objects of the invention is to '5 provide a refrigeratingelement of the flooded type which has a very large heat exchange surfaceand yet has a relatively small number of evaporating chambers.

Another of the objects of the invention is to reduce the number ofjoints heretofore necessary in evaporators of large capacity.

Another object of the invention is to so arrange the refrigerantpassages in a refrigerating element of the character mentioned so as topromote the circulation of refrigerant and escape of oil deposited inthe evaporating chambers.

Still another object is to provide an im- 7 proved arrangement ofrefrigerant conduits 80 secured to fins or plates.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing, wherein a preferred form of the present invention is clearlyshown.

In the drawing: v

Fig. 1 is a vertical section-of a refrigerating cabinet showing myimproved refrigerating '0 element in end elevation;

Fig. 2 is an enlarged end elevation of the refrigerating element;

Fig. 3 is a section on the line 33 of Fig. 2; i

Fig. 4 is a diagrammatic view, on a reduced scale, of a modified form;and

Fig. 5 is a similar sectional view of a modified construction.

It has previously been proposed to construct evaporators having a headerforming a reservoir for liquid refrigerant and a number of ducts orloops of conduit depending from the header and attached to fins orplates, usually by soldering. Where it is desired to construct anevaporator of large capacity there are several objections to this typeof evaporator as heretofore known. If a tube is attached to a fin toincrease its'heat ex change surface there is a limited area of the 6 finover which heat will be conducted to the tube at a sufficiently rapidrate to provide satisfactory refrigeration. Consequently heretofore whenit was desired to make a refrigerating element of large refrigeratingsurface, either a large number of small fins were used or ifl'arge finswere used, a large number of tubes were secured to the fins relativelyclose together. Either type of construction necessitates a large numberof joints between tubing and the header. Joints are undesirable firstbecause they are expensive to make and second because they form pointsof weakness in the evaporator which are apt to develop leaks from onecause or another.

One of the features of the present invention is the provision of anevaporator of great heat exchange surface having a small number ofjoints.

Referring to the drawing 10 designates a refrigerating compartment orcabinet cooled 70 by a refrigerating element generally denoted by 11.The refrigerating element includes a header 12 forming a reservoir forliquid refrigerant and a number of loops of tubing 13 for circulatingrefrigerant, each loop being formed in a plane and soldered throughoutits len th to a plate or fin 14. Each plate is prefera 1y of such sizeas to occupy substantially an entire. side or back wall of the cabinet.-The refrigerating element may be conveniently sup orted from' this sidewall of the cabinet by olts l6 and spacers 17.

Liquid refrigerant is admitted to the header by an inlet connection 19and maintained at a constant level therein by means of any known floatvalve, for example that shown in the patent to Osborn 1,556,708.Evaporated refrigerant is withdrawn from the header through an outletconnection 20 above the liquid level. The tubes 13 are secured theheader in any suitable manner, as by detachable pipe couplings,soldering, or otherwise. Each tube is connected at both ends to theheader below the liquid level, preferably at the bottom, and so is keptflooded with liquid refrigerant.

Where refrigerant conduits are soldered to fins as above described ithas been found that there is a limited area along the conduit throughoutwhich the fin will transmit heat 1 to the conduit at a sufiicientlyrapid rate to be efiective as a practical refrigerating surface. Thisdistance depends upon the temperature difference to be maintainedbetween the refrigerant in the conduit and the atmosphere to berefrigerated, as well as the thickness of the fin, but for a given setof conditions there is a fairly definite and determinable distance fromthe conduit beyond which the fin is ineffective, practically speaking,as a refrigerating surface. That is, while surfaces at a greaterdistance than this will of course absorb some heat and the fin willtransfer some of this heat to the conduit, the re-- sistance to suchheat flow is so great that the amount of heat which reaches therefrigerant is negligible for practical refrigerating purindication ofthis range in ordinary practice,

r 24 of the coil to the header.

it may be said that when refrigerant is being evaporated in the conduitthe portion of the fin within the refrigerating range will become coatedwith frost. It will thus be seen that the factor which limits therefrigerating power of a fin of this sort in given circum stances is thedistance from any given portion of the fin to the refrigerating agentand not the amount of refrigeration which can be supplied at someconcentrated point such as the refrigerant conduit. The maximumpermissible distance has been determined by experiment by attachin aconduit to a plate or fin in the manner in icated and evaporating therefrigerant inthe conduit.

The coils 13 are arranged in serpentine.

fashion from top to bottom of the fins and so distributed that no pointof the fin is farthe'r away from some point ofthe conduit than thefrosting or refrigerating range of the conduit. Each tube 13 may consistof a pair of serpentine-coils arranged as in Fig.

I 3. Each serpentine coil, and in fact the com.-

plete loop 13 is entirely devoid of both horizontal passages and reversebends in a vertical direction, that is each serpentine portion consistsentirely of inclined passages 22 all of which slope upward from thelowest point This provides a refrigerant'path which throughout itsentire length slopes and thus facilitates the escape of evaporatedaseous refrigerant, as well as oil which may e carried into the tubes insolution, and there deposited by the evaporation of the refrigerant. Ihave found that where a serpentine tube of this character includeshorizontal passages of any appreciable length, oil and gaseousrefrigerant may be retarded or trapped in such passages and offersuflicient resistance to the evaporation and removal of refrigerant asto materially reduce the refrigerating capacity of the evaporator. Thep1tchor slope of the inclined portions 22 is the minimum which willpermit the rapid escape of gas and oil, in order that the loops may beplaced as close together as possible. That is, the points 24 and 26 mustbe placed no farther apart than twice the refrigerating range of thetube, and at this distance apart, the length of the passages 22 can beincreased until the minimum slope is reached. This condition determinesthe maximum 'size of fin which can be refrigerated by a single tube.

Where the vertical height of the fin and coil is very large, I find thatthe speed of circulation of refrigerant in it, and consequently therefrigerating capacity of a given evaporator, maybe materially increasedby providing a straight vertical passage between the lower end of theserpentine coil and the header. Such arrangement could be effected byconnecting ,a straight tube between the point 24 and the header. Iprefer that the tubing forming the coil shall have no joints within thearea of the fin because joints make the coil diflicult to attach to thefin and are objectionable for other reasons. Consequently I prefer toform the coils as shown in Fig. 4 in which two coils 13 are attached toeach fin, and each coil includes a serpentine portion 30 and a straightportion 31. In this construction the entire length of the coil is devoidofjoints.

The plates 14 are held rigidly together in spaced relation by means ofbolts 32 and spacers or collars 33.. This forms a rugged structureconsisting of a plurality of refrigerating plates spaced apart toprovide air circulating flues between them. The distance apart of theplates is such that when the plates have become coated with frost in the.ordinary practice there will be sufficient space between the frostedplates to provide ample air circulation.

It will be noted that each coil is always flooded with liquidrefrigerant and that all the coils are connected to the header inparallel. This arrangement keeps the temperature along eachconduit-uniform, and the temperature of each conduit the same. By

this means the entire surface of each fin is an spacers 17' placedbetween the supporting wall and the adjacent plate or fin.

A bafile may be placed adjacent the refrigerating element 11, ifdesired. A suitable type of baflle is designated at 40. This baffle maybe made of nonconducting) materialif desired, such as wood. It may esupported 1 at the ends from the side walls of the com- 7 11 may besupported.

partment 10 or may be supported from the ceiling or floor thereof. Bolts42 may be placed between the baflie 40 and the wall of the compartment,on which bolts the element A drain pan 43 may be placed underneath 1 theelement 11 to receive the products of conmay be provided with one ormore fins on plates 114 held together by bolts 132 and spacers 133similar to those used in the other .modifications. A header 112 may beprovided with loops of tubing 113 similar to the tubing 13, 22, 26 ofFig. 3. At a point corresponding to point 24 of the said Fig. 3anupwardly directedtube 150 may join the tubing 113 and the header 112 forsubstantially the same purpose as in Fig. 5 but with a joint at 124. Theelement 111 may be otherwise similar tothe element disclosed in Figs. 1.2 and 3.

It is apparent that there will be a temperature gradiant of the fins,that is, the outer edges of the fins will be somewhat warmer than thecentral parts because the circulating air flowing over the central partswill be precooled by the outwardly extending portions, also, the centralportion is protected from the relatively warm air by the header 12. Byplacing the ducts 31 or 150 in the central parts of the fins, verylittle, if any vaporization takes place in these ducts and they thusprovide down-flow ducts for feeding the serpentines. In this manner,,there will be a prevalent flow or positive flow of refrigerantdownwardly through ducts 31 or 150 and upwardly through the serpentines.and this positive flow minimizes oil logging of the serpentines in thattype of evaporator in which a quantity of oil is contained in theevaporator.

\Vhile the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A refrigerating element for refrigerating apparatus comprising incombination a header forminga reservoir for liquid refrigerant and anevaporating element connected to the header, said evaporating elementincluding a planar heat exchange plate, a serpentine coil of tubingconnected to the header and secured in intimate thermal contact withsaid plate, said coil consisting entirely of inclined passages, -themaximum distance apart of adjacent passages being not greater thantwicethe refrigerating range of said tubing.

2. A refrigerating element for refrigerating apparatus comprising incombination a header forming a reservoir for liquid refrigerant and anevaporating element depending from the header, said element including aheat exchange plate in longitudinal alignment with the header and a pairof .coils of tubing connected to the header and attached in intimatecontact with said plate, each coil including a straight portionextending vertically from said header substantially the entire length ofsaid plate, and a serpentine portion connecting the lower end of saidstraight portion with the header, said serpentine portion being devoidof horizon-' tal passages and projecting longitudinally beyond theheader, the straight portion of said coils being adjacent each other.

3. A refrigerating element for refrigerating apparatus comprising incombination a header forming a reservoir for liquid refrigerant, aplurality of planar coils of tubing connected to the head and dependingtherefrom, each coil including a serpentine portion devoid of horizontalpassages, a heat exchange plate thermally connected to each of thecoils, tie means holding said plates together and spacing means holdingsaid plates apart to form air circulating flues.

4. A refrigerating element for cooling air flowing thereover, saidelement including header means for liquid refrigerant, a plurality ofvertically extending serpentine evaporator chambers having the outletsthereof connected with the header means and having the inlets thereof atthe lower ends, fin means below the header thermally connected with saidchambers, and down flow duct means connecting the inlets with the headermeans, said duct means being disposed so as to be thermally protectedfrom relatively warm circulating air.

5. A refrigerating element for cooling cirlower ends, fin means belowthe header thermally connected with the chambers, and down flow ductmeans connecting the inlets with the header means, said duct means beingdisposed so as'to be thermally protected from relatively warmcirculating air;

6. A refrigerating element for cooling circulating air flowingthereover,-said element including header means for liquid refrigerant,p'late'type fin means below the header, a plurality of substantiallyplanar serpen- .tine evaporator chambers lying parallel with the finmeans, said chambers being thermally connected with the fin means andhaving the outlets thereof connected with the header means and havingthe inlets thereof at the lower ends, and down flow duct meansconnecting the inlets with the header means, said duct means beindisposed so as to be thermally protected rom relatively warm circulatingair.

7. A refrigerating element for cooling circulating air flowingthereover, said element including header means for liquid refrigerant, aplurality of wertically extending ser pentine evaporator chambershavingth'e outlets thereof connected with the header means and havingthe inlets thereof at the lower ends,.fin means below the headerthermally connected with said chambers, and down flow ducts eachconnecting one of the inlets with the header means, said duct meansbeing disposed so as to be thermally protected from relatively warmcirculating air.

8. A refrigerating element for cooling circulating air flowingthereover, said element including header means for liquid refrigerant, aplurality of vertically extending tortuous evaporator chambers devoid ofhorizontal passages, said chambers having the outlets thereof connectedwith the header means and having the inlets thereof at the lower ends,fin means below the header thermally connected with the chambers, and 7down flow ducts each connecting one of the inlets with the header means,said duct means being disposed so as to be thermally protected fromrelatively warm circulating air.

9. A refrigerating element for cooling circulating air flowingthereover, said element including header means for liquid refrigerant,plate type fin means below the header, a, plurality of substantiallyplanar serpentine evaporator chambers lying parallel with the fin means,said chambers being thermally connected with the fin means and havingthe outlets thereof connected with the header means and having theinlets thereof at the lower ends, and down flow ducts each connectlngone of the inlets with the header means, said ducts being disposed so asto be thermally protected from the relatively warm circulating air. t

In testimony whereof I hereto afiix my slgnature.

JESZSEWG. KING.

